In multiple effect distillation systems, a series of distillation chambers, or “effects”, are utilized in order to distill water to remove contaminates and otherwise unpalatable substances therefrom. Each chamber or “effect” of a multiple effect distiller is maintained at a preselected internal pressure, and specifically, each subsequent chamber is maintained at a pressure lower than the immediately preceding chamber. This controlled, descending pressure from the first to the last chamber enables the steam generated from one chamber to be transferred to a subsequent chamber and utilized as a heat exchange medium so as to vaporize the feed water within each chamber. That is, as the pressure in each successive chamber is less than the prior chamber, the corresponding boiling temperature of the water is also lower, and thereby enables utilization of the steam of the previous chamber to be used as the heat exchange medium for the subsequent chamber. The re-use of steam as a heat exchange medium increases the efficiency of the distillation process.
As multiple effect distillers become more commonly utilized in retail establishments, such as supermarkets, convenience centers, and the like, an additional problem confronted by multiple effect distillers is the inability to access and perform routine maintenance while minimizing the size of the distiller and/or the space surrounding the distiller required to do such maintenance. As an increasing number of retailers desire to provide their consumers with a source of distilled water, multiple effect distillers are being employed in commercial environments where floor space translates into selling space and, consequently, effective space utilization must be observed. However, existing multiple effect distillers, if they provide easy access in order to permit routine maintenance, require additional floor space around the distiller for access to the different components at different sides of the distiller. In some designs, the distiller may be reduced in size, but then, although compact, the reduced size comes at the expense of easy access to the components.
Another concern with existing multiple effect distillers is their exclusive reliance upon a main controller to operate the distiller. With most multiple effect distillers, a main electrical controller controls all of the distiller's components and, consequently, each component of the distiller must be separately wired to the main controller. Connecting each component to the main controller increases the complexity of the manufacturing and installation process. Further, the number and length of the electrical wires which must be attached to the main controller increases the probability of an electrical malfunction.
Additionally, reliance upon a main controller increases the complexity and cost of identifying and subsequently rectifying a malfunction. Often, if one element of the main controller fails, for example, an element which monitors one of the chambers, it is difficult to isolate that one element within the circuit board, and, thus, frequently requires the replacement of the entire circuit board.
The inability of many multiple effect distillers to efficiently and adequately separate the steam from any entrained water droplets is an additional issue confronted by the distillation industry. Failure to successfully separate the steam from the water in each chamber adversely effects the purity of the distillate resulting from the distillation process. Specifically, the distillation process may be compromised by any entrained water droplets from one chamber being transferred into the heat exchanger of a subsequent chamber, and thereby adding impurities to the distillate in the subsequent chamber.
Sensing of the feed water level within each chamber also presents issues for existing multiple effect distillers. As the feed water level in each chamber must be monitored and maintained within a particular range, a sensor must be used. Normally, such a sensor is either of the conductive probe type or mechanical valve type, both of which require direct contact with the boiling water within the chamber. Contact between the heated fluid and the sensor over time causes the sensor to become coated or damaged by substances contained in the boiling water. Also, when using conductive probe technology, the large variation of water conductivity in water supplies based upon their geographical location has reduced the precision with which the conductive probe technology can be utilized in multiple effect distillers.
In most multiple effect distillers, subsequent to the distillation of water through the series of chambers, the distillate and volatile gases contained within the feed water are subjected to a final condensation phase. After final condensation, the distillate and volatiles are forwarded to a separation system which sequentially separates the volatile gases from the distillate and forwards the volatile gases to a volatile disposal or drain chamber. Normally, the separation system includes a volatile separation chamber configured to separate the volatile gases from the distillate. The volatile gases are then transferred from the volatile separation chamber into a volatile disposal chamber wherein the volatile gases are mixed with a fluid, and brought to a temperature suitable for disposal in the operator's drainage system.
The water forwarded to the volatile disposal chamber, commonly referred to as “blowdown water,” is usually at an elevated temperature and transferred from the last distillation chamber or effect. Cooling water is utilized to cool the blowdown water and the volatile gases prior to the water and gases being discharged to the drainage system. The cooling water is sprayed into the volatile disposal chamber and mixes with the blowdown water and volatile gases. In order to conserve water, the cooling water source is cycled on and off for a predetermined period of time. However, as current regulations control the temperature at which a fluid may be introduced to a municipal drainage system, as well as the prevalent use of polymeric pipes which are more susceptible to damage at high temperatures, in order to bring the fluids to an adequate temperature, the cooling water source is often left on. As the cooling water is not separated from the blowdown water and volatile gases, continuously maintaining the flow of cooling water greatly increases water consumption and prohibits the cooling water from being recycled. This in turn increases the operating costs and reduces the efficiency of the distillation system.
In order to maintain distillate purity and palatability, it is routinely required to drain the distilling chambers in order to clean the chambers. With existing distillers, an operator must slide a pan or container under the distiller frame and empty the distilling chambers. As the operator must manually open the distilling chamber, the proximity to the drain at which an operator must be positioned during the draining procedure may cause injury to the operator as the hot water from the distilling chamber splashes onto the pan positioned therebelow.
Therefore, there exists a need for a multiple effect distiller which is efficient, reliable and safe to operate, and which overcomes the problems confronted by existing multiple effect distillers.